Antifungal antibiotics from Pisolithus tinctorius

The antibiotic compounds p-hydroxybenzoylformic acid [2-(4′-hydroxyphenyl)-2-oxoethanoic acid, pisolithin A] and ( R)-(−)- p-hydroxymandelic acid [( R)-(−)-2-(4′-hydroxyphenyl)-2-hydroxyethanoic acid, pisolithin B] were isolated from the growth culture of Pisolithus tinctorius. Both of these metabolites, and a few structurally related compounds, were shown to inhibit spore germination and cause hyphal lysis to a significant number of phytopathogenic and dermatogenic fungi. Hence, it was concluded that P. tinctorius aids its host plants by providing protection against disease-causing microorganisms.